* doc/invoke.texi (-fshrink-wrap): Document.

	* doc/invoke.texi (-fshrink-wrap): Document.
	* opts.c (default_options_table): Add it.
	* common.opt (fshrink-wrap): Add.
	* function.c (emit_return_into_block): Remove useless declaration.
	(record_hard_reg_uses_1, record_hard_reg_uses, frame_required_for_rtx,
	requires_stack_frame_p, gen_return_pattern): New static functions.
	(emit_return_into_block): New arg simple_p.  All callers changed.
	Use gen_return_pattern.
	(thread_prologue_and_epilogue_insns): Implement shrink-wrapping.
	* config/i386/i386.md (return): Expand into a simple_return.
	(simple_return): New expander):
	(simple_return_internal, simple_return_internal_long,
	simple_return_pop_internal_long, simple_return_indirect_internal):
	Renamed from return_internal, return_internal_long,
	return_pop_internal_long and return_indirect_internal; changed to use
	simple_return.
	* config/i386/i386.c (ix86_expand_epilogue): Adjust to expand
	simple returns.
	(ix86_pad_returns): Likewise.
	* function.h (struct rtl_data): Add member shrink_wrapped.
	* cfgcleanup.c (outgoing_edges_match): If shrink-wrapped, edges that
	are not jumps or sibcalls can't be compared.

	* gcc.target/i386/sw-1.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@179553 138bc75d-0d04-0410-961f-82ee72b054a4